Tire change and problems

So I changed the rear tire on the Mondial.
Why is it that when people change tires they leave the old tube in place? I can't tell you how many bikes I've changed the tire on that have ancient tubes installed still. This one might not have been the original 1955 tube, but it was an old one. When was the last time Michelin manufactured 2.50 x 19 tubes in Italy? Thats how it was marked, (in English!)," Michelin Made in Italy"! And the rubber was frayed so it had to go.
I want to plug this video, it is a great aid for me to to remember the proper procedure:

You can just click through to part 2.
And the Bead Buddy is a great tool! Really helpful.

So with any project, something has to go wrong... this time? The wheel bearings are shot! Luckily I have some spares. Those will go in tomorrow. And then maybe I should check the front bearings...